Rongrong Shi

Cobalt hydroxide nanosheets and their thermal decomposition to cobalt oxide nanorings.

We demonstrate herein that single-crystalline beta-cobalt hydroxide (beta-Co(OH)(2)) nanosheets can be successfully synthesized in large quantities by a facile hydrothermal synthetic method with aqueous cobalt nitrate as the cobalt source and triethylamine as both an alkaline and a complexing reagent. This synthetic method has good prospects for the future large-scale production of single-crystalline beta-Co(OH)(2) nanosheets owing to its high yield, low cost, and simple reaction apparatus. Single-crystalline porous nanosheets and nanorings of cobalt oxide (Co(3)O(4)) were obtained by a thermal-decomposition method with single-crystalline beta-Co(OH)(2) nanosheets as the precursor. A probable mechanism of formation of beta-Co(OH)(2) nanosheets, porous Co(3)O(4) nanosheets, and Co(3)O(4) nanorings was proposed on the basis of the experimental results.

Shape-controlled synthesis and characterization of cobalt oxides hollow spheres and octahedra

We demonstrated that single-crystalline cobalt monoxide (CoO) hollow spheres and octahedra could be selectively synthesized via thermal decomposition of cobalt(II) acetylacetonate in 1-octadecene solvent in the presence of oleic acid and oleylamine. The morphologies and sizes of as-prepared CoO nanocrystals could be controlled by adjusting the reaction parameters. Cobalt oxide (Co(3)O(4)) hollow spheres and octahedra could also be selectively obtained via calcination method using corresponding CoO hollow spheres and octahedra as precursors. The morphology, size and structure of the final products were investigated in detail by XRD, SEM, TEM, HRTEM, DSC, TG, and XPS. The results revealed that the electrochemical performance of cobalt oxide hollow spheres is much better than that of cobalt oxide octahedra, which may be related to the degree of crystallinity, size, and morphology of cobalt oxides.

Selective synthesis and magnetic properties of uniform CoTe and CoTe2 nanotubes

Uniform CoTe and CoTe2 nanotubes could be successfully synthesized via a facile hydrothermal co-reduction route based on the precipitate slow-release controlled process.